Category: Material Handling Fans

Industrial Fans & Noise

The important factor to consider is the fan’s blade pass frequency, which is a pure tone produced when the blades of the fan wheel (impeller) rotate past the housing cut-off sheet in centrifugal fans, or the turning vanes, in axial fans. The blade pass frequency is calculated by multiplying the number of blades times the rotating speed in revolutions per minute. If this frequency matches the natural frequency of the ductwork, it can excite the ductwork, which can cause it to resonate, thereby increasing the noise level. Because of this possible increase in sound, and because certain pure tones are irritating to people, the sound output of the blade pass frequency should be investigated when sound reduction is desired. The next factor to consider is the fan design. Generally a fan operating at peak mechanical efficiency will produce less noise, because high efficiencies result from minimal air turbulence within the fan.

The sound generated by some fans can be a potential hazard to personnel in close proximity to the fan, and the sound can be transmitted, via the ductwork connected to the fan, to all areas serviced by the fan. Because of these concerns, fan manufacturers publish sound ratings for their products to serve as a guide for selecting fans to meet sound specifications, and to assist acoustical consultants in predicting the total noise levels in specific environments. This article provides basic information to help understand fan sound ratings and how to apply them. Like any mechanical device, fans generate sound, which emanates naturally from the turbulence of moving air, the mechanics of moving parts of the fan, and from vibration.

Air turbulence within the fan increases the sound coming from the air movement. The noise resulting from air turbulence is a major factor in the sound levels of a fan in a specific application. Further, duct work can transmit this turbulent noise to all areas serviced by the fan. Factors contributing to air turbulence include the resistance to flow, flow separation along fan surfaces, and shock related to abrupt changes in the direction of airflow, pressure, or velocity. A lower noise level can be achieved by reducing air turbulence. This can be done by considering several factors related to air movement when selecting fans.

Industrial Centrifugal Fans Design

There are four basic centrifugal fan wheel designs – forward curved, backwardly inclined, radial, and radial tip – and a variety of axial flow wheel designs. Each wheel design has unique sound characteristics due to the way they handle air, and the efficiencies they can achieve. Fan speed does not always determine which fan will be quieter. For example, centrifugal fans have higher amplitudes at lower frequencies, while axial fans exhibit higher amplitudes at the higher frequencies. The amplitude of the blade pass frequency on an axial fan is higher and more pronounced than on backwardly-inclined fans, and commonly will have amplitude peaks at multiples of this frequency.

Backward Inclined Fans

Of the four centrifugal designs, the backwardly inclined fans are the most efficient, and therefore, the quietest. Those with airfoil-shaped blades offer the highest efficiencies, for clean air environments, while those with single-thickness blades can be used in applications where light dust or moisture is present, although the efficiencies are somewhat lower.

Axial & Vaneaxial Industrial Fans

Certain types of axial fans offer the next highest efficiencies. An excellent example is the Vaneaxial fan that uses airfoil shaped blades in an in-line flow design. This fan is used to handle high volumes of clean air at low pressures, which is a typical ventilation application.

Radial Blade Fans

Radial fans are typically low efficiency, open designs for special purpose applications, such as bulk material handling, or exhausting / supplying lower volumes of air at higher pressures. A radial fan will be much louder than a backwardly-inclined fan operating under the same volume and pressure conditions.

Radial Tip Fans

Radial Tip fans, commonly used to handle larger volumes of air that contains particles or material, exhibit sound characteristics similar to the radial fans. The sound spectra of radial and radial tip fans contain amplitude spikes at various frequencies, and a noticeable spike at the blade pass frequency.

Forward Curve Fans

The forward-curved fan design operates at speeds that are much slower than the other fan types, which results in lower noise levels from mechanical operation and vibration. However, because of its modest efficiencies, a forward curved fan may be noisier than a backwardly-inclined fan when operating at comparable volume and pressure. The sound spectrum of the forward-curved fan shows a slower rate of reduction in amplitudes than the other centrifugal types, and because of the large number of blades, the blade pass frequency occurs much later in the spectrum and is not predominant.

Industrial Fan Components

The moving components of the fan – the motor, bearings, and drive – produce sound. This too can be transmitted through the system via the fan structure or shaft, or when these components are in the airstream. Motor sound will vary with speed, enclosure, electrical characteristics, and even the manufacturer. Antifriction bearings can be used to reduce bearing noise, and proper drive selection will reduce the likelihood of belt hop, or slap. Of course, proper maintenance must be employed to keep the moving parts running smoothly, and quietly.

Excessive vibration can significantly add to the overall noise level of an installation. This will occur if the fan or any of its components are not adequately balanced, if the fan is installed on an insufficient foundation, or if the fan is not properly isolated from other system components. For example, it is not uncommon for the fan’s support structure or ductwork to have a natural frequency at the fan’s operating speed or blade pass frequency, either of which can cause the system to resonate at that frequency, increasing the sound levels, and the possibility of damaging the installation. These risks can be eliminated by changing the speed of the fan, installing appropriate isolation, and / or detuning of the fan or affected system components.

dBA is a useful measurement for evaluating the overall noise level at a particular location, but this measurement takes into account all of the sound sources affecting that particular location, which include the sounds from all equipment in the area, natural sounds of the environment, and from other environmental factors. Some of these factors are the current physical properties of the air such as temperature, humidity, and pressure, whether the location is outside or inside, the size and material of the room. All of these affect the sound pressure experienced by the listener, and recorded by the sound level meter.

Published fan sound power ratings and corrections only reflect noise created by air turbulence within the fan. Because of the infinite variables, mechanical noise and vibration noise are impossible to accurately predict, and are not included in the rating.

Additional information can be found at the Northern Fan web site http://northernindustrialsupplycompany.com/products/ventilators.html

Industrial Fans Canada

People these days opt to use fans for their ventilation needs. A mechanical fan often has many uses around the house and inside buildings. This versatile appliance can serve as a cooling instrument especially during the summer and it can also be used during winter to push warm air down in order to heat a room.

Axial fans, centrifugal fans

In the industry, there are many types of fans such as axial fans, centrifugal fans, crossflow fans and bladeless fans. These types of fans have features, structures and benefits. Each one offers different processes and ways of balancing the temperature. Their usage also depends on the kind and size of the room that needs ventilation. This enables engineers to choose the right kind of ventilation that will coincide with the design they have in mind for their buildings.

Axial Fans

Axial fans are the typical household fans we see every day. This type of fan has three or more blades that rotate to allow air to pass through and circulate around a room. Axial fans are operated by electricity to balance the temperature and permit air to flow inside a room.

Damper Fan

A damper fan is a duct-like device used to neutralize temperature through ventilation ducts. There are many damper manufacturers who produce fire dampers that help prevent the spreading fires in buildings and houses. These fans are designed to close once subjected to heat and/or fire. Engineers and architects are incorporating fire dampers in their design to effectively reduce the damage that a fire can cause.

A dampers manufacturer makes sure that its products are safe for use by consumers. They make certain that their products materials are of the highest grade and quality so as not to risk the safety of the building where the fans will be used.

Centrifugal Fan

A centrifugal fan manufacturer sells fans that are quite different from the other types of fans. This type of fan is composed of different instruments which control the fans speed. It is a typically larger mechanism compared to other fans to accommodate bigger structures like office buildings and factories. All of these fans aim to maintain the convenience of the people regarding temperature balance.

Industrial Fans – Types

Different models of fans are available in the market in various unique designs, integrated with the latest technologies and low power consumption facilities. The variety of elegant fans includes integrated gear box and push button switch to suit any decor.Many stylish fans with double ball bearing are available in lots of colors which are integrated with dynamically balanced blade for maximum air delivery.The use of radial blower in the fans helps in moving air perpendicular to the blower axis and provides relatively low flow rates and high pressures.

Types of Blowers & Fans

The wide range of blowers and fans includes non-decorative Ceiling fans, wall mount fans, decorative ceiling fans, single centrifugal blowers, dual centrifugal blowers, radial wheel blowers, cast aluminum blowers, high pressure blowers, belt driven blowers, explosion proof and food safe blowers, high temperature oven circulating fans, industrial fans and also stainless steel and other alloy fans are available in the market. Finest quality, durability and enduring performances of these fans are catching more attention of the market these days. A wide range of axial flow fans is designed to provide efficient trouble free service & reduce the initial and operating cost to minimum. Apart from the fans there are various other products like air blowers, air scrubbers, axial fans, axial flow fans, centrifugal blowers, cyclone seperators, dust collecting equipment, dust collector, exhaust blowers, fan blowers, industrial blowers and many more.

Non-Decorative Ceiling Fans are integrated with the low power consumption facility with double ball bearing for maximum air delivery and available at very reasonable price. Non-Decorative Ceiling Fans are high speed fans, which are available with four blades to provide maximum air delivery and best for all small rooms. Non-Decorative Ceiling Fans has variety of designs and colors available at the best competitive prices. Non-Decorative Ceiling Fans consists of power saving technologies which make it more unique and high monopoly holder in the competitive market.

Wall Mount Fans are available in sleek and stylish look with less noise and delivers maximum air pressure. Wall Mount Fans are integrated with aluminium blade coated which increases its life and also gives an elegant look to your room. Wall Mount Fans are available in many colors like Blue, Red, Brown, Cherry and lots more.

Decorative Ceiling Fans are one of the most demanding ranges of fans in the market. The aluminium body with golden touch offers a unique look and suits any decor. These days, the latest technology of power saving in fans attracts the market and consumers as well.

Industrial Extractor Fans

Industrial extractor fans come in a wide variety of shapes, sizes, and strengths so it can be difficult to choose the best one for your restaurant kitchen. There are roughly seven different sizes that are available from 315mm to 630mm which can be mounted in a few different ways. Many businesses prefer the axial style of fan as it can be used for a wide range of applications. This article will discuss these machines and hopefully make your choice of fan a bit easier.

One of the common drawbacks of industrial extractor fans is how loud they are. This can be such a problem that most restaurant managers choose to run them only when the amount of steam, smoke, and pollutants in the air reaches an intolerable level. However, there are some high end models that can run in a Quiet Mode that doesn’t make that much noise at all and even can be run all the time if you choose. You may even want to run the fan a bit after your staff has finished for the day in order to clear up any residual pollutants that may remain in the air.

If you are currently looking at the different options of industrial extractor fans you have available, you will have to decide whether you would like a model that uses ducts or one that uses filters. The former choice is the most efficient as it can take the polluted air directly out of your building and replace it with clean air. Your other option, the filtered models, do not do as well because they will recycle the same air within your building only they run it through a charcoal filter first to make it cleaner. While a ducted model is preferred in most situations, they can be a bit more on the expensive side. Not to mention, you may not have the space necessary to fit the ducts.

It is important that you find industrial extractor fans that have been built to last. Therefore, try to find a model that is built from steel as this is a durable metal that is sure to last. Also be on the lookout for one that is coated in corrosion proof paint and has steel wire guards as well for optimum protection. It is also a good idea to pay special attention to the kind of motor each model features. Try to find one that is lightweight, but works well and is built to last.

One final thing you will have to take into consideration is how you will install your fan. You will find that most axial industrial extractor fans may be installed in various ways such as:

– Mounted on the wall with special brackets

– Placed freestanding in the center of the room

– Hung from the ceiling with chains

– Inline with your ductwork

Additional information can be found at the Industrial Fan Blower company web site http://www.industrialfanblower.net/Index.htm

Industrial Ventilators for Ventilation

Industrial ventilation is of paramount importance to ensure the safety and well-being of employees. In industries where employees are subjected to dangerous chemicals, vapours and gasses on a daily basis, effective industrial ventilation can mean the difference between life and death. The basic concepts behind industrial ventilation are quite simple, but for it to be effective, the ventilation system needs to be installed by an experienced engineer.

Industrial Ventilation Methods

Industrial ventilation is a method of controlling employee exposure toxic chemicals, volatile airborne substances and flammable vapours by removing the contaminated air and replacing it with clean, fresh air. Used in a variety of different industries where poisonous vapours may be a problem, industrial ventilation is most often employed to remove welding and solvent vapours, oil mists and poisonous or volatile dust.

But, industrial ventilation may not always be necessary. True, it should be preferable for the continued health of your employees, but regulations suggest that industrial ventilation only becomes compulsory when:

Industrial ventilation should also be considered before respirators. Not only is the system easier to maintain, but, in the long run, is a much more cost effective method of air purity control.

Industrial Ventilator Options

There are a number of industrial ventilation options available depending on the circumstances of your industry’s circumstances. The most basic is indoor quality ventilation that aims to provide fresh air throughout a building as part of the existing ventilation system. This option is primarily used in offices but can be effective in small industries where the concentration of contaminants is low.

Easy to maintain and inexpensive to set up is dilution ventilation. This form of industrial ventilation uses large and powerful exhaust fans to extract contaminated air and to draw in clean air. It is very effective in clearing flammable vapours but is less effective for metal fumes or large concentrations of highly toxic materials. Depending on where the industry is located, the incoming air may require a lot of cooling or heating before it can be introduced into the industrial ventilation system, increasing the cost of using the system.

Dilution Ventilation Principles

Dilution ventilation uses the simple principles of displacement and dilution to function. Some of the contaminated air is removed and replaced with large amounts of fresh air. The concentration of the contamination is effectively lowered, making it safer for people to work in the area.

A more localised industrial ventilation system is local exhaust ventilation. This system captures the contaminations at the source and expels it before it has a chance to disperse into the air. For highly toxic contaminants or high concentrations, this industrial ventilation is probably one of the best. It does not require large amounts of fresh incoming air since the exhaust of contaminants is localised. This effective ventilation comes at a higher cost and more frequent maintenance, however.

Local Exhaust Ventilation

Local exhaust ventilation works like a vacuum cleaner forcing contaminated air to move from a high concentration to a low concentration. It is perhaps one of the most effective industrial ventilation systems because it removes the contaminants at the source before it has a chance to spread.

There are effective industrial ventilation systems available for any industry. Some are simple to use, like dilution ventilation, while others are specifically made for highly toxic environments, like local exhaust ventilation. Whatever the decision, as long as the industrial ventilation keeps your employees safe from the contaminations of the substances they work with, it is doing its job.

Selecting an Industrial Fan

The air delivering capacity of axial flow fans ranges from 100 to 500,000 cubic feet per minute (3,000 to 15,000 cubic meters per minute). Impellers usually have blades with airfoil cross-sections.

Axial Fans

In an axial fan, the effective progress of the air is straight through the impeller at a constant distance from the axis. The primary component of blade force on the air is directed axially from inlet to outlet and thus provides the pressure rise by a process that may be called direct blade action.

The blade force necessarily has an additional component in the tangential direction, providing the reaction to the driving torque : this sets the air spinning about the axis independently of its forward motion.

As compared to curved sheet blades, aerofoils can apply greater force to the air, thereby increasing maximum pressure and can maintain better efficiency over a wider range of volumetric flow. Also by increasing the thickness & curvature of the inner sections, the blades can be made stiffer, this limits flutter and allows the impellers to be run at higher speeds.

Selection of a a right fan one should consider such factors like cost optimization, power rating & noise levels govern the selection of a fan suitable for a given application. Various combinations are possible to meet any given duty or operating requirements for best performance, lesser noise, power and cost characteristics.

Once the volume of airflow and the static pressure of the system are known, it is possible to specify a fan. The governing principle in fan selection is that any given fan can only deliver one flow at one pressure in a given system. To select a fan one must consider the following parameters:

– total airflow required

– total operating pressure

– fan installation space

The fan efficiency is defined as the ratio of air power (output) to shaft power requirement (input). An optimally designed fan impeller with improved aerodynamics requires less shaft input power for desired delivery of air volume with total pressure rise as per the system requirement. With reduced shaft power requirement, there is a commensurate reduction in energy consumption.

Thus the fan efficiency is directly contingent upon selection of fan and the operating point relevant to the system resistance.

The way fan impellers (blades or rotors) are designed, the amount of air they can move decreases as the pressure they are working against increases.

The airflow vs. pressure information for a particular fan is called the fan performance data. The performance of a fan depends on the size, shape & speed of the impeller. The fan performance data is essential for selecting fans as per the desired airflow and system pressure.

Most fans are tested using procedures specified by Air Movement and Control Association International Inc. (AMCA), Illinois, USA. The fan under test is mounted near the outlet of the test rig and air in-flow through the rig is varied by the movable gate assembly situated at the other end of the test rig.

The airflow through the rig is determined by measurement of the pressure differential and simultaneous readings are taken of the static pressure developed by the fan, air velocity at the exit side, power consumed by the fan driving motor etc.

Fan performance curves and data show how much pressure and airflow a given fan can produce at a given speed. This data is based on the system resistance (pressure) occurring away from the fan. Fan performance curves are developed by fan manufacturers based on the testing of a prototype fan fabricated based on the theoretical design.

The axial flow fans are widely used for providing the required airflow for heat & mass transfer operations in various industrial equipment and processes. These include cooling towers for air-conditioning & ventilation, humidifiers in textile mills, air-heat exchangers for various chemical processes, ventilation & exhaust as in mining industry etc. All the major industries use large number of axial flow fans for operations, such as :

Axial Fans & Axial Ventilators

Canada Fans fans are the finest quality blowers available for efficient movement of corrosive, humid, or polluted air, gases, and fumes. These fire-retardant and corrosion-resistant plastic fans are specially designed and especially suited for hostile applications where coated metal blowers typically corrode. Canada Fans fans are proven thoughout the world and clearly recognized for superior quality, reliability, and efficiency.

Axial Flow Fans

The axial flow fans are widely used for providing the required airflow for heat & mass transfer operations in various industrial equipment and processes. These include cooling towers for air-conditioning & ventilation, humidifiers in textile mills, air-heat exchangers for various chemical processes, ventilation & exhaust as in mining industry etc. All the major industries use large number of axial flow fans for operations, such as:

– Power Generation Facilities

– Petroleum Refining & Petrochemicals

– Cement Industry

– Chemicals & Pharmaceuticals

– Fertilizer Production

– Mining Industries

– Institutional Ventilation, etc..

Fiberglass Reinforced Plastics (FRP) provide the desired non-corrosive quality to the fan blades, resulting the operation of fans even in the very aggressive environment. Lightweight FRP fans also ensure a low moment of inertia, minimum wear & stress on motor, bearing and drive system.

Hollow FRP blades reduce material & installation costs and possibility of damage to the fan & drive during sudden stops. Composite structural design can be tailor made by using glass fibres in various forms (woven mat & rovings) in right direction while moulding the impeller with resin thus imparting the desired mechanical strength by improving its structural stability and enhanced mechanical properties.

Aerofoil design of fan impellers ensures higher efficiency, lower noise levels & less power consumption. The aerodynamically designed impellers of fans, fabricated by composite material can be an excellent alternative to ensure enhanced efficiency & appropriate energy savings apart from a wide gamut of critical advantages.

The potential of FRP composite for various applications is very wide. In view of the crucial need for developing indigenous capability in composite technology the main advantage of FRP fans is their utilization and application of composite as an important performance material in various sectors and to improve upon the laboratory-industry linkages towards development & commercialisation.
Canada Fans Co. is a major supplier of plastic and fiberglass fans and blowers for industry applications where aggressive media must be moved. Plastic fans include polypropelene, PVC, PVDF, fire retardant and UV resistant PPs.

Some applications for Corrosion and Chemical Resistant Fans worth to mention here are:

Vaneaxial Adjustable Pitch Fans

Canada Fans Vaneaxial Adjustable Pitch Fans are used in applications where demands vary with system or seasonal change. Blade pitch is manually set to increase or decrease performance. Blades are easily adjustable externally at the hub. Available in compact direct drive models.

Spray Booth Design Canada Fans Vaneaxial Fans

Spray Booth Design Canada Fans Vaneaxial Fans are available in standard belt drive arrangement 9. These fans are designed for use in spraybooth installations, or in a variety of applications where requirements make it necessary to clean the fan periodically. Standard accessories include: inlet / outlet cones, inlet bell, screensfor fan, cone, or bell; belt guard, weather proof motor and drive cover, spark resitant construction with aluminum wheels, or steel wheels with bronze tipped blades; support legs, suspension clips, shaft seals are also available as standard options.

Clamshell Design

Canada Fans Vaneaxial Fans are used primarily in applications where ready access to the interior of the fan is desired. The entire bearing assembly can be removed quickly and easily, without removing the fan from the stack. Heavy duty pillow block anti-friction bearings with split inner cylinder are standard. Clamshell design vaneaxial fans are available with steel wheels and aluminum wheels.

High temperature construction on Canada Fans vaneaxial fans can be furnished with optional high temperature construction for oven exhaust, or combusting gases exhaust applications.

Corrosion resistant construction and chemical duty construction on Canada Fans ventilators are available as well. For corrosive environment all Canada Fans vaneaxial fans are available in FRP construction, as well as in 304 SS, 316 SS, or 316 L stainless steel construction. Special coatings are optional and selection is made based on the application.

Industrial Fans Uses and Applications

Fans have helped to create safer and more pleasant internal environments for hundreds of years. The invention of mechanical fans is found in the industrial revolution and the first commercially viable electric fans were made available to the US public early in the 1930’s.

Fan Manufacturing and Ventilation Solutions

Today the technology behind fan manufacturing and ventilation solutions have sky-rocketed to create fans for virtually every use from cooling devices in a server room; to ventilation in a manufacturing plant; to keeping a bathroom clear of damp air.

Generally speaking, fans and their accessories can be divided into 3 main usage categories: domestic use, industrial use and commercial use.

Industrial Fans

Industrial Fans will often have a very robust requirement and it is essential to involve experienced engineers with the installation of such ventilation. Other than just determining whether the fans will be required for air supply or for exhaust functions (i.e.: as an extractor fan) the engineer or installation technician will need to be keenly aware of both the working temperatures of the units as well as any thermal protection qualities of its associated housing or frame.

Some industrial fans will come with controllable speeds which can be very handy in a changeable internal environment, especially with regards to saving on ventilation costs at times when the air regulation needs of an area are reduced. Special features such as built in monitoring and systems integration come in handy when working in a potentially hazardous environment for example when chemicals or volatile substances are involved. Generally speaking, fire resistance and corrosion resistance are both ‘plus’ features for any industrial ventilation setup. Above the ‘plus’ one will need to consider the health and safety requirements of your region such as vibration or noise control and air quality regulations related to worker health.

Commercial Fans

Commercial Fans would not have as robust a requirement but the overall integration of fans into the building structure and management system is key to efficiency. Automatic ventilation in refrigeration units or in rooms that will typically contain many people at the same time will keep areas safe and comfortable. Operational areas such as server rooms (also known as data rooms) and elevators will need to provide adequate ventilation, usually in the form of extractor fans, to remove excess heat generated by the operating machinery which often runs continuously. Commercial ventilation also acts as a barrier to unwanted external influences such as insects, pollution and natural allergens.

Domestic Fans

Lastly domestic fans find their main purpose in providing less costly air quality solutions. There are two ways to cut costs with a domestic ventilation solution. You can invest in a ‘cheap and cheerful’ unit from the beginning resulting in a smaller initial cost or you can install a slightly more costly fan and ducting system with operational features that help you save on heating and ventilation costs in the long run. There are a wide variety of low energy extractor fans and ventilation units are now available for kitchens, washrooms and living rooms. In addition heat recovery units now help you to use the heat from stale air that is being extracted to warm-up fresh air that is being pulled in by your system.

Additional information can be found at the Industrial High Pressure Blower Company web site http://www.highpressureblower.net/pressureblower.html

Power Roof / Wall Exhausters

To do a satisfactory job of eliminating excessively hot air, it is usually essential to have powered wall and / or roof exhausters. These fans should also help to control air pressure within the building whether it be negative or positive pressure. The most effective way to incorporate wall or roof exhausters into a system will be discussed below. A large number of buildings use exhaust fans and/or power roof ventilators to exhaust fumes, smoke, dust or other contaminants unavoidable in the operation of the business. As a result, these buildings are frequently under a severe negative pressure. This condition can create problems in many areas of operation. Examples are: (1) reduced efficiency of exhaust systems that are working against each other; (2) down drafts in flues, that may extinguish pilot lights and cause explosions and tire; (3) severe drafts around windows, doors and other locutions when air seeks to enter the structure. The solution to problems of this kind is usually found in the use of supply fans or “make-up” air ventilators. During the hot weather period, these fans become a valuable source of fresh, cooler, outside air to replace the superheated air being exhausted. If they arc correctly sized and coordinated with the exhaust fans, an effective ventilation system may be achieved.

Industrial Fans for Ventilation

A work stoppage or strike may occur if the problem of personnel discomfort is unresolved. The benefits from a solution to such a situation are enormous. In plants where there is a high density of employees and many manual operations involved, an improvement in the environment can produce substantial benefits in terms of increased production, reduced errors, and a decline in complaints and absenteeism among employees. In other circumstances, the attentiveness of an audience or student group may be a factor that spells success or failure for the project. There is a Buffalo Fan case history where a high ambient temperature had actually reduced the capacity of a big power turbine. To obtain rated performance by the machine, an improvement in the room ventilation and cooling system was necessary. When this was accomplished, the plant management was amazed to find an equivalent improvement in the efficiency of the employees who were required to work in this same environment with the machine.

Roof / Inline Exhaust Fans

If the exhaust and supply air requirements of a building have been carefully engineered and installed, and there continues to be a high instance of worker discomfort, the problem usually relates to the matter of air circulation. Typical examples of worker discomfort are found in areas where exhaust fans are roof mounted and air supply is through windows and wall openings. Air flow is generally from the window opening to the nearest roof exhauster. The cooling effect on the individuals in the area is negligible. To be effective, air flow must be at or near floor level. In this way, occupants obtain maximum benefit from the fresh, cooler air; they receive the added comfort of air circulation over their bodies and they are not adversely affected by the superheated air being exhausted from the building.